Pigeons are not only devoted partners — they are highly intelligent and complex beings that possess abilities most humans don't even know exist. Pigeons have tiny magnetic crystals in their beaks that act like biological compasses that allow them to sense Earth's magnetic field and navigate accurately. They can also detect sounds too low for humans to hear and read polarized light patterns in the sky that are invisible to humans. Pigeons can also count, recognize themselves in mirrors, and learn abstract concepts. They rank among the top ten most intelligent beings on the planet. For more on the brilliance of pigeons, see "The Genius of Birds" by Jennifer Ackerman.